Tableted polychlorophenol salts



' pound sets to a mass resembling'pl'aster of Paris Patented Feb. 6,1940 TABLETED' POLYCHLOROPHENOL SALTS Kent R. For,v St. Louis, and IraHatfield, Webster Groves, Mo-., assignorstc:-Monsanto..Chemical Company,St. Delaware v No Drawing.

Louis, M0., a corporation of Application October 9, 1937, Serial No.168,202

6 cl ims. (01. 23-245) {The present invention relates to watersolublepolychlorophenol salts, particularly pentachlorophenol salts, and refersto a new and improved physical 'form oi'such 'salts'which permits oftheir more advantageous handling in commerce and in industry 'Withoutsubstantial impairment of their ease of solubility.

I Pentachlorophenol and tetrachlorophenol salts in the dry powderedcondition or in'the form of "theirmonohydrates, particularly the sodiumsalts ofthese phenols, are very light in bulk and areeasiiy'blown'about; In handling such materials it is-difiicult to avoiddusting. These salts produce local irritation of the skin and mucousnembranes of the nose and throat and on continued exp'osur fmay produce adermatosis of the skin characterized either by redness or anacneformeruption. The salts even when-inhaled in small amounts produce sneezingfollowed by excessive rhinorrheathat is, excessivedischarge of mucousfrom the nostrils. hazardous and have been-avoided because of thespecial precautionsrequired in their use.

Sodium pentachlorophenate or the monohy-. drate in the dry powderedcondition readily dis-' solves in water by stirring. However, when itismerely .wetted with sufficient water, hydrate formation occurs-and theresulting hydrated-com- -Which is far more difficult to dissolve.Although the hydrated salt is less hazardous to handle, it issurprisingly more difiic'ult to use because of its failure to dissolverapidly. Furthermore, dry sodium 'pentachlorophenate' which has beenexposed to the atmosphere Will over a period of time develop varyingproportions of water-insoluble components. a loss to the consumer. Theprimarycbject of the present invention is to produce Water-soluble saltsof polychlorof phenols in a-form such that they are readily andcompletely soluble in water, are non-dusting, are not appreciablyaffected by exposure to the atmosphere, and. which-dissolve quickly andcompletely even after storage.

We have found that-the above objects are attainedin anespeciallyadvantageous manner by producinglthe polychlorophenol salts inthe 'form of .tablets or briquettes in the manner described hereinafter.l

difificulty in attaining the objects of the present inventionhas beenencountered in making acompacted mass which While in vcompactformshould-not be fragile and aiiected by atmospheric moisture and which, onthe other hand, should.

Such materials, therefore, i are 9 The insoluble material representswhen droppedintowater dissolve rapidly therein. Excellent tablets orbriquettes can by produced by simple moistening of sodiumpentachlorophenate with water and molding, but the resulting tabletsresemble set plaster of Paris, are diflicultly soluble, and aretherefore entirely unsatisfactory. Anhydrous "sodium pentachlorophenateitself can be compressed into a tablet or briquette but themass'crumbles on standing. Any binding agents containing water which areadded to aid in tableting or briquetting, for example, sodium silicate Isolutions, produce hydration of the salt, Whereas bituminous, tarry orsimilar binding agents are not usable because they, of themselves, beingin- 115 soluble, make the resulting tablet-or briquette extremelydifficult to dissolve. Furthermore, When sodium silicate is used-asa'bindin'g agent for the tablets "or briquettes, it 'pro'duces'a powderwhich adheres to the -metal equipment and the resulting tablets are notreadily disengaged from the mold after compression.

On the other hand, when starch is added to the material as a bind- 'ingagent it yieldsa tablet of more or less -lamellarform, as a result ofwhich it crumbles and-disin'tegrates readily. The application of thecommon methods heretofore known, failed to produce coherent masses ofrequired solubility in Water. v H

The present invention is based upon our unexpected discovery thatsodiumtetrachlorophenates and 'pentachlorophenate of controlled moisture"content -will form into coherent tablets or briquettes whencompressed ina particular manner, hereinafter described in full, to produce thedesired'objectsset forth above. In such tablets or briquettes the outersurfaces are in more or less coherent form whereas the interior 'is-"inpar- 7 ticulate 0r granular formQ The tablet is impervious :toatmospheric moisture and air to a remarkable degree and the salt in theinterior of the tablet or briquette is thereby protected fromdecomposition and dehydration.

The tablets, briquettes or cakes are substantially noncrumbling,"non-hydroscopic and quescenuthat is, they neither absorb nor liberatewaterto any appreciable extent. The small content of moisture required.for producing such co- 'herent tablets or briquettes is withoutsubstantial effect on thesolub-ility in water of the formed 50 mass.When. the salt is thus used in the form of coherent tablets there islittle danger of the occurrence or dusting. Elven should any. smallparticles become disengagediroin a formed cake non delior tablet byabrasion ordroppingthey are in a compressed or agglomerated form and notin the form of a fine bulky powder that is a hazard.

In an example of the method of practicing the invention a powderedsodium pentachlorophenate containing from approximately 3% to 10% ofmoisture or water is used. Such moisture or water is probably held inthe salt as water of crystallization, inasmuch as the salt itself issub-' stantially dry. This water content may be controlled in theproduction of thesalt or water may be incorporated into dried sodiumpentachlorophenate powder of a lower moisture content by careful uniformmixing in the customary manner, care being taken to avoid any localconcentration of water which would result in hydration to the lesssoluble form. By controlling the drying operation used in theproductionof the salt this moisture content can be maintained mostconveniently. This optimum moisture content isvarlable to some extent,the limits beingapproximately 3% to about which corresponds to fromroughly A; to 4 molecules of water for each molecule of anhydrous sodiumthan 70% or thereabouts of water are fluid susv pensions or solutions,for example, parts of v tion are intended particularly for,thepreparapentachlorophenate. At about a water content of the productproduces a hydrate which sets similar to plaster of Paris. Withproportions of water from about 30% to as high as 70%, the products aresolids. Products having more dry sodium pentachlorophenate in about '75parts of water yields a clear solution at room ternperature. For bestresults in tableting or briquetting, a water content of about 3% to 10%is most satisfactory. Smaller water contents require greater pressure inthe tableting operation and yield tablets which disintegrate tooreadily.

Products of higher water content (containing quetted in thefollowingmanner: The powder is efed to a tableting machine ofconventional design in which the pressure applied to the mold is fromapproximately 5,000 to 20,000 pounds per from about 10% to 20% water) donot compress with any substantially greater ease than those of about 10%water content, and since these products have a higher water content, thesodium pentachlorophenate becomes more expensive to ship and the tabletsor briquettes themselves have a smaller margin of safety with regard toany detrimental effects which might result from any extraordinaryexposure to moistureor accidental wetting.

The powdered sodium pentachlorophenate of controlled moisture content istableted or brisquare inch. .The resulting molded mass, which at thisstage is easily broken when dropped, is then disintegrated or granulatedin a cob mill or a suitable grinding machine to yield particles of about1 to 10 mesh in size, the preferred size being approximately 4 mesh. Theparticulate compressed material or granulations are then subjected to asecond compression under approximately the same conditions in a mold.

The mold in this first compression can be of any shape or size but themold used in the final compression (recompression) should be thatcorresponding to the form in which the final tablets are desired. Afterthis second compression the resulting tablet is firmly coherent and willeasily resist abrasion or breaking during handling and transportation.The recompressed tablet is not deliquescent or efiiorescent and issubstantially impervious to atmospheric moisture or carbon dioxide. Onstanding exposed to the atmosphere for long periods there is nosubstantial disintegration of formation of water -insoluble com pounds.To prepare'aqueous solutions of the salts from the tablets, agitation isdesirable, preferably agitation by means of aujet of steam through thesolution.

- Instead of using one preliminary compression f and granulation asabove, the salts'may with advantage be subjected to two or morepreliminary compressions to produce compacted particulate masses orgranulations. The preliminary and final compressions may be conducted ifdesired on suitable rotary briquetting machines, al-

though in this event more than two compressionsand granulations areusually necessary since such briquetting machines permit the applicationof great pressures but do not in any one compression reduce the bulk ofthern'aterial sufficiently.

The pressures which areapplied to the mold v in the tableting operationare'somewhat variable,

but are within a preferred range of from about 5,000 to 20,000 poundsper square inch. Less pressure may be used in the preliminary molding ascan be well understood. The pressures to betion of baths for thetreatment of wood toprevent the growth of sap-staining organisms andother fungous growths. Insuch use a precipitation of thepolychlorophenol appears in the bath after prolonged Wood treatment;This precipitation in such baths can be prevented and the quality of thetablet or briquette is furthermore markedly improved by theincorporation with the salt of a small proportion of sodium hydroxide vor potassium hydroxide or other suitable strong alkali. Proportions offrom 1% to 1 0% of sodium hydroxide have an especially advantageous effeet on the quality of the resulting tablet and.

aqueous baths made with such sodium-hydrox+ ide-containing tablets canbe used for long .periods without any difiiculties from precipitation ofthe free chlorophenols. The sodium hydroxide can be advantageouslyincorporated inthe original preparation of the salt, that is, prior tothe I drying of the salt. I Tablets containing alkali in theseproportions, surprisingly, are not affected to, any substantial extentby prolonged exposure to the atmosphere, any more than tablets notcontaining alkali.

,To aid in solubilizing the tablet or it is desirable also to add asmallproportionof a Wetting agent such as a sulfonated high molecular weightalcohol or preferably asulfonated alkylated aromatic hydrocarbon such asbriquette I that known to the industry under the trade name Santomerse.For this purpose less than 1% by weight of Santomerse is'ample. I

Additions of coloring agents, substances which 7 exert a synergisticaction upon the polychlorophenol; talc or other mold lubricants, andsimilar components of a secondary nature in small 1 proportions may bemade prior to the compression without necessitating changes in themold.-

ing procedure. I

The invention is particularly applicable to the tableting or'briquetting of sodium tetrachloro- The optimum understood that mixturesof sodium tetrachlorophenates and sodiumpentachlorophenate are alsoinfluenced to some extent by the factors pointed out hereinabove butwill be within the range of 3% to 20% which has been. specified forsodium pentachlorophenate.

Inasmuch as this specification contemplated. What we claim is: i

1. A formed compressed coherent mass consisting predominantly of sodiumpentachlorophenate having a moisture content of from 3% to 20% andcontaining from 1% to 10% of sodiumhydroxide, and being characterized bybeing readily and substantially completely soluble in Water, saidproduct beingobtainedby compression of the powdered salt, subsequentgranulation of the compacted mass, and final molding thereof.

2. A formed compressed coherent mass consist ing predominantly of vasodium salt selected from the group consisting of the sodium salts oftetrachlorophenol and pentachlorophenol having a moisture content offrom approximately 3% to 20% and containing from 1% to 10% of sodiumhydroxide, said tablet being characterized by being readily andsubstantially completely soluble in water.

comprises pre-v ferred embodiments of the invention it is to beunderstood that it is not limited to these specific 3. A formedcompressed coherent mass consisting predominantly of sodiumpentachlorophenate having a moisture content of from approximately 3% to20% and being readily and substantially completely soluble in water.

4. A recompressed tablet consisting predominantly of a sodium saltselected from the-group consisting of the sodium salts oftetrachlorophenol and pentachlorophenol having a moisture content offromapproximately 3% to 20% and containing from 1% to10% of sodiumhydroxide,

said tablet being readily and substantially completely soluble in water.

5. A recompressed tablet consisting predominantly of a sodiumpentachlorophenatehaving a" moisture content of from approximately 3% to20% and containing from approximately 1% to 10% of sodium hydroxide,said tablet being characterized by its resistance to breakage andabrasion and by being readily and substantially completely soluble inwater.

6; The method of tableting a salt selected from the group consisting ofthe sodium salts of tetrachlorophenol and pentachlorophenol, consistingin incorporating uniformly with said salt a proportion of water suchthat the water content of the salt corresponds toifrom 3% to 20% of themass I and a proportion of sodium hydroxide such that themass containsfrom 1% to 10% thereof, and

c: thereafter by means of compression and disintegration producing amass of said salt of reduced bulk in particulate granular form, andsubse-' quently subjecting said granulated mass to a final molding toproduce a coherent tablet which is readily and substantially completelydissolved in water.

KENT R. FOX. IRA HATFIELD.

